Science Quarks and Quirks: November 2013

Saturday, 30 November 2013

Palaeopathology Series, Part 1: Venereal Syphilis

This is the start of an occasional series on Palaeopathology (the study of ancient diseases) which I enjoyed studying as an undergraduate. I expect a large amount of sympathy for the many grotesque images I have had to endure in the quest for knowledge, especially considering the nature of Part One- an Introduction to Venereal Syphilis.

Venereal Syphilis is an infectious disease that is a member of a group of disorders called Treponemetoses, caused by the bacterium, Treponema pallidum subspecies pallidum. The infection occurs in three stages: the primary stage where a painless lesion occurs at the entry site of infection, the secondary stage as a skin rash develops (along with mucous membrane lesions) and finally the tertiary stage, marked by the infection spreading to the organs in the Central Nervous System, as well as the heart and skeleton. In 20-30% of cases tertiary symptoms can manifest 5-20 years after the original infection. Without our good friend the humble antibiotic, the numbers of cases reaching this stage in history were immense. Luckily for Palaeopathologists, the fact that symptoms can be found on the skeleton allows for the analysis of historical diseases including disease history, geographical spread and the ability to predict similar infection courses in the future.

The most frequent symptoms of Venereal Syphilis found on the skeleton are bi-lateral lesions most commonly occurring on the tibia and skull (frontal, parietal and nasal-palatial regions). If the infection advances to the Central Nervous System then Neurosyphilis can occur. This infection of the brain and spinal cord can cause many debilitating effects when living, such as headaches, numbness in the extremities and seizures. In historical cases, indirect evidence of this type of disorder can be found as a Charcot’s joint, which is caused by repeated trauma occurring at the joints, due to a lack of pain perception.

Analysis of the skeletal symptoms of Venereal Syphilis has been used in attempts to deduce the mysterious emergence of the disease. The earliest known reports of Venereal Syphilis came from Naples in 1495, when a ‘plague’ broke out among the French King, Charles VIII’s troops. It is thought that when they later disbanded the disease was spread throughout Europe. How and when Venereal Syphilis arrived in Europe is a matter of great controversy with two opposing schools of thought contesting a different historical background. The first believes that there is an association with the timing of Christopher Columbus’ return voyage to Europe from North America, with the bacteria transported aboard ships. The other believes there is evidence for Venereal Syphilis being present in the Old World before the voyage in 1493. The difficulty in evaluating the history of the disease is that the remaining evidence of Syphilis found on the skeleton can often be mistaken for other disorders (such as Tuberculosis) and there has been recent controversy over non-peer reviewed research on supposed syphilitic skeletal remains found in pre-1493 Europe, being represented in the media.

Recently, the Columbian hypothesis has been refined with the belief that the Columbus voyage transported a Treponemal bacterium that was nonvenereal, and which later adapted under new selective pressures in the Old World to become Venereal Syphilis. While this theory is intriguing, a problem arises due to the short time in which the bacterium would have had to adapt and become sexually transmitted in this new environment (especially if the first known case was in Naples, 1495). Phylogenetic studies on treponemal disease may be the next step in illuminating the history of this interesting disease, going beyond the limitation of osteological observation.

This is just a brief overview of a few of the skeletal symptoms and the controversial emergence of one of the most virulent diseases in history. I encourage you to research further and increase your disgust, but be warned- what has been seen on google images can never be unseen!

Saturday, 23 November 2013

The Weird (and often Traumatic) World of Animal Sex

Anyone who has ever had to witness the horrific site of mallard duck (Anas platyrhynchos) mating when taking a young child for an innocent ‘feeding the ducks’ experience, will know the discomfort it can produce. For those who do not, the defining reason for this discomfort is the fact that mallard ducks often violently rape females during mating. A little known fact is that females have developed their own anatomical quirks, in what can be described as an evolutionary sexual arms race. As the males have phalluses big enough not to require consent from females when mating, female vaginas have spiral channels which twist in the opposite direction to that of the male genitalia. In some cases, ducks have evolved cul-de-sac pouches which prevent sperm from fertilising an egg, which allows the female to have some control of the second half of the genetic material that will be passed on to her offspring.

Recent research has discovered another traumatic mating ritual in the animal kingdom. A species of sea slug (Siphopteron species 1) has been found to stab each partner centrally in the forehead with an organ called a penile stylet, during copulation. As the slugs are hermaphrodites (having both sets of reproductive organs) there is a reproductive advantage to acting as the male when mating, due to the potential to create more offspring by being free to fertilise other slugs after copulation. By stabbing each other in the head and injecting a secretion which has the ability to control the other slug’s behaviour and prevent it from mating again, this may provide more time for the sperm to fertilise the eggs and force the slug into the female role.

Another interesting mating technique is found in a certain species of snake. Red-sided garter snakes (Thamnophis sirtalis parietalis) mate in a mass orgy of slithering reptiles. This is less traumatic for the animal but still pretty vile for the snake fearing masses out there. The female produces a pheromone to attract male snakes in great numbers, which creates a mating ball of competing males surrounding the female. The pheromone can provide the following information to the male: correct species, population, sex, season, reproductive condition and age. The successful male who gets to mate with the female deposits a gelatinous copulatory plug that can reduce the chances of the female re-mating and works as a spermatophere (a protein matrix from which sperm are released as the plug dissolves). This mechanism increases the chances of successful fertilisation when competition is fierce and time is short.

Red-Sided Garter Snake Mating Ball- Not for the squeamish!

Other research emphasises the profound weirdness of mating in this species of snake. So called, ‘she-males,’ can also produce small amounts of this female sex hormone to trick male red-sided garter snakes into courting them. As snakes are cold blooded, a slower, weaker snake would have an advantage i

n creating warmth (needed in the cooler spring months of the mating season) by attracting a mating ball to itself.

These examples of the weird and wonderful ways in which animals create the next generation, only just scratch the surface of the intriguing research being carried out on the topic. It is a subject that both fascinates and disgusts in equal measure and will continue to cause adults many awkward trips to the park with their own offspring.

Saturday, 16 November 2013

Our Parents are Aliens?

Panspermia is the idea that life on a planet can be established by distribution from one celestial body to another, via natural means. The original concept was proposed in 1865 by Hermann Eberhard Friedrich Richter and over the years it has gained remarkable popularity (if not solid evidence). Scientists are researching the potential for microbes to survive the harsh environments of space, atmospheric entry and the impact on Earth necessary for the hypothesis to be true. This may all sound suspiciously like Ridley Scott’s ‘Prometheus’ but I can assure you that the science is far more interesting than any mediocre film could convey.

Past research has suggested that DNA is highly vulnerable to destruction by cosmic radiation, but another molecule call

ed RNA may have had the potential to kick-start life on Earth. This is because RNA has the ability to reproduce without help (eg. enzymes). It can, on its own, create secondary and tertiary structures which could catalyse the production of other RNA molecules. If life on Earth started off with an ‘RNA world’ and there was an eventual transition to DNA, then RNA-viruses may have taken a role- if the Panspermia theory is to be believed. However, the huge difficulty in this concept is that viruses need a host to survive (a factor sadly lacking when forming new life on a planet) and unless evidence suggests ancient viruses could live without this basic requirement, the hypothesis falls flat.

While the Panspermia theory seemed dead in the (lifeless) waters, later evidence has suggested that ancient life-forms may have been capable of surviving the harsh atmospheric conditions of space. In 2011, it was found that certain types of microbes (brilliantly named extremophiles for their hardy resistance to the most extreme conditions- including nuclear reactors) could survive in frozen environments such as underground lakes in Antarctica. The adaptations necessary to live in such a severe environment would be essential if they were to be successfully carried through space on ice-cold comets. Furthermore, experimental data has proven that organic molecules could survive prolonged atmospheric re-entry.

This week’s latest research suggests organic material can survive the capture, transport and impact of a high force contact event. The Darwin crater in Western Tanzania (a crater left from an impact with the earth 800,000 years ago) created impact glass due to the high temperature and pressure associated with the collision. Analysis of the glass has found surprising evidence for the organic remnants of the ancient ecosystem which was hit by the meteor. This is the first study of its kind to present evidence of life surviving either on the terrestrial surface or inside a meteorite that has impacted Earth. While this research does bring some weight to the Panspermia hypothesis, the Darwin crater is relatively small and it has yet to be proven that life could survive a much bigger impact.

Though still only a theory, the Panspermia hypothesis does have some weighty scientific evidence to pin down the more sci-fi elements. Life on earth may not have extraterrestrial origins, but the potential for microbes to survive in the most inhospitable environments may provide interesting developments in the future.

Friday, 8 November 2013

A Cautionary Tale of Anatomy

Surgeons from Belgium have recently published research detailing the anatomy of a ligament in the knee joint. Whilst its existence was confirmed by a surgeon in 1879, it has taken 134 years to fully describe its anatomy. This study has illuminated a murky area of human anatomy: which structure connects the femur with the outer front of the tibia. While this enigma may now be understood, the functions of this structure (in terms of the biomechanics of the lower limb) are still unknown. What makes this research slightly unnerving is the amount of surgery that takes place in this area, to counteract the common sports injury of a tear to the anterior cruciate ligament. To put it plainly, this is surgery on an area of anatomy that is not fully understood... today... in 2013. While there are distinct regions of the body that remain a mystery for the time being (the brain being the most obvious choice) the structure of the knee is not one that quickly comes to mind.

There are other examples where a lack of anatomical knowledge is less of a restriction to surgery than one might hope. As recently as 2008, studies were created testing the optimal implantation angle for sacral nerve stimulation. This procedure is used to treat bladder dysfunction by supplying electric impulses to sacral nerves connected to the bladder, suppressing oversensitivity in this area. In order for the electrode to reach the nerve, it needs to be inserted into the 3^rd or 4^th sacral foramen (holes in the posterior bone), detectable only through palpating the area. The success of the procedure depends on how close the surgeon can insert the electrode into this small space and results vary. Considering the first study on sacral nerve stimulation was in 1988, a lot of time (and surgery) has passed, where a lack of anatomical knowledge has been detrimental to the success of the procedure. Fortunately, research is being undertaken into the best angle of insertion and the most successful methods of detecting the correct foramen (though the application of techniques practised on cadavers may still hold some problems in practise). To provide some comfort, this method is only undertaken as a last resort, when other forms of treatment, such as medication, no longer work or are unsuitable.

It is of interest that the medical marvels carried out every day, are performed on an anatomy that still retains some enigmas. While we pride ourselves on the scientific leaps made since the time ailments were treated by bloodletting, any smugness we feel is reduced by the reminder that our understanding is not complete. I can only apologise for any worry caused to those soon to be going under the knife, however they may yet be placated with the knowledge that future researchers still have jobs to do.

Further reading:

Bolton, J.F. & Harrison, S.C. (2009). Neuromodulation 10 years on: how widely should we use this technique in bladder dysfunction? Current Opinion in Urology, 19(4), pp. 375-379.
Buchs, N.C. et al. (2008). Optimizing electrode implantation in sacral nerve stimulation- an anatomical cadaver study controlled by laparoscopic camera. International Journal of Colorectal Disease, 23(1), pp. 85-91.
Claes, S. et al. (2013). Anatomy of the anterolateral ligament of the knee. Journal of Anatomy, 223(4), pp. 321-328.

Credit:<a href="http://www.flickr.com/photos/50946274@N02/4849499648/">Rob Swatski</a> via <a href="http://compfight.com"> and </a> <a href="http://creativecommons.org/licenses/by-nc/2.0/">cc</a>